The migratory habits of Gadus merlangus and G. pollachius are examined n i relation to the variations in the rate of infection of these fish with Lernaeocera branchialis. A sudden increase in infection in estuarine and inshore waters is found to coincide with the offshore migration of the main stock. The infected fish apparently linger behind and may live for some time in the old habitats after the arrival of the next recruitment. The offshore migrants are seldom infected, and it is probable that infection does not take place in water deeper than about 5 fathoms.

The possible immediate causes of this “lingering” phenomenon are examined, and two suggestions are made as to the nature of the physiological upset brought about by the presence of L. branchialis on these gadoids. Other factors influencing the distribution of the parasite are discussed.

The relative susceptibility of the different species of gadoids to infection with species of Lernaeocera is examined as far as the data allow.

The molecular diversity of dinoflagellate algae of the genus Symbiodinium in symbiosis with ten species of scleractinian coral, sea anemone and scyphomedusa in the Mediterreanean Sea was investigated by restriction analysis and sequencing of polymerase chain reaction-amplified fragments of SSU and LSU rRNA genes. All species bore Symbiodinium of clade A, apart from Bunodeopsis strumosa, which had clade B. The clade A sequences clustered with a previously described group, ‘temperate-A’, known only from the Mediterranean and Atlantic coasts of the UK and France. It is concluded that clade temperate-A is prevalent, but not universal, in the Mediterranean.

Conflict between dolphins and fisheries is an important management issue in many parts of the world. In 2002, we examined the extent of depredation in the Italian small scale fishery by means of in situ interviews. Overall, 245 landing sites were investigated, representing 11.09% of the whole Italian artisanal fleet. The association between the commonly used artisanal fishing gear and the interacting fauna was investigated by means of correspondence analysis. Set gillnet and trammel nets were the types of the fishing gear most vulnerable to dolphin depredation; the interaction with these gear amounted to 66.4% while fish damage was reported in 72.2% of the cases. A regional ranking of the interactions in terms of both fishing gear alteration and fish damage, shows that the problem is most pressing in the Friuli, Campania, Sardinia and Apulia regions. This study is the first attempt to monitor dolphin–fisheries interactions and assess depredation rates in Italy, providing information on the areas where future investigation should be concentrated.

The epithelial receptors of Nassarius are primary sense cells. The sensory endings are abundant on the tentacle tips, anterior border of the foot and ventral external surface of the siphon tip. Densities are a small multiple of 1032 endings/mm2.

Type 1 ciliated endings are of ubiquitous occurrence. The ultrastructure of type 1 endings is uniform, though the static and motile bundles of sensory cilia may be distinguished by the random or uniform orientation of the ciliary subfibrils and basal feet. Ciliated receptors probably include both chemo- and mechanoreceptors.

A distinct ultrastructural type of sensory ending (type 2), confined to the siphon tip, consists of a small pit in the peripheral dendrite close to the epithelialsurface. The pit contains whorled microvilli and a few cilia. It may be photoreceptive.

A small amount of convergence of sensory information may occur in peripheral nerve.

The activity of oxygen in sea water and standard oxygen electrode potentials at a range of temperatures have been computed.

Accurate values for the thermodynamic ionic product of water, Kw, found by Harned & Hamer, have been applied to the calculation of the activity of hydroxyl ion in sea water from pH measurements.

The activity of water in sea water has been computed from the lowering of the freezing-point.

From these data the theoretical reversible oxidation-reduction potential of sea water has been calculated.

.Typical data for the irreversible potential in the pH range 1-8 have been derived from Hoar's results with which experimental determinations made by Dr Atkins agree. Thus the oxidation-reduction potential of sea water is controlled solely by the oxygen system.

INTRODUCTION

Cephalopods may be divided into five types according to their buoyancy. Members of several families such as the Octopodidae, Loliginidae and Ommastrephidae are negatively buoyant and must swim to stay in midwater and are therefore highly muscular animals. Others have mechanisms to make them neutrally buoyant so they can remain suspended in midwater without effort. Nautilus, Spirula and cuttlefishes have low pressure gas-filled chambers and their flesh is muscular and non-buoyant (Denton & Gilpin-Brown, 1973). Squids of one family, the Gonatidae, have a low density oil in their livers to give buoyancy but most of their body is muscular. Some oceanic octopods have very watery tissues in which lighter chloride ions replace sulphate ions (Denton & Shaw, 1961). In 12 of the 26 teuthoid families the buoyancy is provided by low-density ammonia-rich solution in their body and head tissues or in an expanded coelomic cavity (Clarke, Denton & Gilpin-Brown, 1979). These ammoniacal squids are extremely abundant in the oceans of the world and form a large part of the diet of birds, cetaceans, seals and fish (Clarke, 1977). When their biomass is estimated from their utilization by predators it is important to know their properties as food and, in particular, their calorific values. As pointed out by Croxall & Prince in a review of the calorific values of cephalopods (1982), all the known values are of muscular, negatively buoyant species because they are of value as food for humans but no measurements have been made on the ammoniacal or oily species which are probably as important, or even more important, in the economy of the ocean (Clarke, 1983).

The general histology of the integument of the ophiuroid Ophiocomina nigra is outlined. Two types of integumentary mucous glands are described in detail for the first time. The first is a multicellular gland, the basal end of which is located deep within the calcareous layer of the integument. The source of the secretion is a variable number of nuclei embedded in a common cytoplasmic mass filled with fine basiphil granules. These cells contributed their secretion to a duct which pursues a tortuous course through the integument. The ducts frequently branch and anastomose so that any one exit pore may extrude mucin derived from a number of separate, polynuclear sources. The structure so formed is, thus, a massive, multicellular gland. Histochemical studies demonstrate that the mucin is a highly sulphated acid mucopolysaccharide. The second type of mucus-secreting unit is a unicellular gland usually located superficially in the calcareous layer or sometimes restricted to the epidermis and distributed universally over the body. The secretion product of these cells is shown histochemically to be a simple acid mucopolysaccharide. The mucin secreted by the tube-foot glands is demonstrated also to be a highly sulphated acid mucopolysaccharide.

The function of these secretions has been investigated to some extent. The massive glands secrete only under conditions of alarm and it is suggested that this mucus serves as a defence against predation. The unicellular glands secrete in a periodic fashion correlated with the act of feeding. This secretion is probably utilized in a suspension-feeding mechanism.

Sponges (Phylum Porifera) are among the most ancestral metazoans and are frequently difficult to identify, even by taxonomic experts, due to their lack of complex morphological characters. However, poriferans are highly diverse, ecologically important and of significant importance to pharmaceutical and biomaterials industries. Therefore, means of unambiguous identification are urgently needed. A DNA taxonomic system, and in particular sponge DNA barcodes, will provide a set of indispensable tools to aid taxonomists and ecologists in the rapid identification of sponge species, which will enhance the discovery of drug-producing species. Here, we will argue for the implementation of a DNA supported taxonomic system and introduce the Sponge Barcoding Project.

The relationship between the calcite skeleton and associated cells in the spines of Echinus esculentus is described. The cell bodies lie in channels within the skeleton and cytoplasmic processes extend from them toward the calcite. Swollen regions of the cytoplasmic processes contain organelles such as mitochondria and various vesicles. The plasma membranes of the cytoplasmic processes appear to spread over the calcite surface which is thus topologically intracellular. A considerable portion of the stereom space is extracellular and contains an extracellular fluid and collagen fibres.

Since the early 1950s a sport fishery for sharks has existed off south-west England. On average some 5000 sharks are taken annually on rod and line between May and October. The catch consists almost entirely of blue sharks, the majority of which are immature or adolescent females, limited numbers of the porbeagle, Lamna nasus Bonnaterre, mako, Isurus oxyrinchus Rafinesque and very occasionally the thresher, Alopias vulpinus Bonnaterre.

Several authors have shown that by feeding bivalve larvae on a mixed algal diet growth is often better than when each of the constituent species of the diet was fed individually (Davis & Guillard, 1958; Walne & Spencer, 1968; Calabrese & Davis, 1970). The criterion upon which the value of the diets has been assessed has almost invariably been larval growth and rarely have the larvae been grown to metamorphosis.

This paper reports the results of a series of trials with Ostrea edulis L. larvae which were fed with three diets. Two were single species diets of Isochrysis galbana Parke and Tetraselmis suecica (Kylin) Butch, while the third was a combination of these two species. Larvae were grown to metamorphosis on each of the diets and then for a further period with a common food to assess the value of the larval diet on the subsequent performance of the spat.

Patella vulgata possesses nine different pedal glands, six of which pour their secretions on to the sole. Proteins secreted by the marginal gland into the marginal groove are used for locomotion, especially when the limpet moves off following a period of adhesion. Another protein-secreting subepithelial gland, sparsely present throughout the foot, is also believed to be used in locomotion. A third gland type is present in the epithelium of the sole. The secretion of these epithelial mucocytes which is a weakly acidic muco-polysaccharide (MPS) is likely to have a locomotory function. Three other sole glands secrete highly viscous acidic MPS. Their secretions are likely to have an adhesive function. The three other glands present in the foot are contained within the side-wall. Of these, two are believed to secrete mucus to protect the animal against desiccation during emersion; and the other, present only in young P. vulgata, pours its acidic MPS secretion into the epipodial streak. This secretion consolidates debris before it is cleared from the pallial cavity; in adult animals, muscular contractions of the foot are powerful enough to clear debris without the help of the epipodial gland.

In Acmaea tessulata the six glands present open out on to the sole and correspond in position, composition and function to the six glands of the sole of P. vulgata. There are no glands within the side-wall.

At the junction between the scyphistoma's scyphopharynx-filament complex and its endoderm is a narrow zone of simple columnar cells. These cells can transform into amoebocytes which collect together and work their way to the aboral end of the polyp, where they secrete a cuticular encasement, thus forming the podocyst.

Light and electron microscopy, as well as histochemistry, show the podocyst to be a lamellated tanned chitin-protein complex covering the protoplasmic contents, which have a nucleated outer clear cytoplasmic layer and a yolky central zone which may be liquefied in places.

The aims of the present study were to investigate food consumption, growth and the dynamics of feeding hierarchies in the same groups of juvenile greenback flounder (Rhombosolea tapirina: Teleostei) fed either high or low rations. Differential food consumption by individual greenback flounder held in groups of 20 showed the presence of feeding hierarchies in which individuals consumed between 0 and 22% of the available food. Inter-individual differences in food consumption resulted in different growth rates leading to growth depensation (measured as an increase in the coefficient of variation for weight). Intra-individual differences in food consumption tended to be larger for flounder which consumed a lower share of the available food. When the group ration was reduced the inter-individual and intra-individual variations in food consumption increased. Consequently, the relationship between inter-individual and intra-individual variation in food consumption tended to become stronger at lower food availability and indicated an increase in the strength of the feeding hierarchies. This study suggests that individual differences in food consumption, mediated through exploitation competition, contribute to growth depensation in this species of flatfish.

Nauplii of the first two stages were obtained from adult Elminius modestus and larvae of all stages, except the smallest, were obtained from the plankton over Essex oyster beds.

Over 200 nauplii of all sizes were measured. Their size distribution, plotted graphically, showed six peaks corresponding to six naupliar stages. The later stages were much more variable in size than the earlier stages.

The size limits and characteristics of each naupliar stage are given. Briefly, Stage I has the fronto-lateral horns pointing backwards. Stage II has the caudal spine much longer than the abdominal process. Stage III has the abdominal process about as long as the caudal spine, but has no carapace fold posteriorly. Stage IV has a carapace fold but no sign of the abdominal appendages. Stage V has the rudiments of these appendages showing indistinctly within the abdomen. In Stage VI the abdominal appendages are prominent.

Techniques for the rearing of monogenean larvae are described.

The new term ‘oncomiracidium’ is proposed for the larvae of monogenetic trematodes.

Eleven new oncomiracidia offish parasites are described, bringing the total now known to thirty-five.

These oncomiracidia are tentatively classified, and the classification is compared with the existing classification of adult monogeneans.

The intertidal distributions of the two varieties of Actinia equina L. defined by Stephenson (1935), var mesembryanthemum and vai.fragacea, have been studied on several shores of the English Channel. The reproductive physiology and iso-enzyme genetics of sympatric populations of the two taxa have been investigated in greater detail on one shore. The genetic results show that the two taxa are reproductively isolated and, overall, the evidence indicates that they are separate species.

Behaviour during homing movements and downstream migration of yellow- and silver-phase American eels (Anguilla rostrata) was observed using continuous ultrasonic telemetry in a tidal estuary. Homing subadult (yellow-phase) eels, non-displaced yellow-phase eels and adult (silver-phase) eels all used tidal currents as a transport mechanism (‘selective tidal stream transport’) and possibly as a means of orienting and moving in an appropriate direction. Yellow-phase eels displaced up the estuary and migrating silver-phase eels moved mostly at night and during ebbing tides. Yellow-phase eels displaced down the estuary moved mainly during flooding tides both day and night. Non-displaced eels used selective tidal stream transport to make long, round trip excursions and to move about their home range. Eels were at or near the surface during most of their movements, but were also vertically active, diving transiently to mid-water or to the bottom. During movements, the eels tended to drift with the current, or to swim slowly in the direction of the current. Although they used the tidal currents effectively as a transport mechanism, they were not precise in timing their movements to maximize transport on each tide. This study demonstrates that both yellow- and silver-phase eels use selective tidal stream transport during movements in tidal habitats and excludes some cues previously proposed to regulate the behaviour.

The British Phycological Society was founded in 1952 to serve as a meetingground for phycologists, and to carry out a co-ordinated scheme of work on the algae of this country. The specific projects included the production of a Flora of British Marine Algae and the publication of a series of biological studies of individual genera and species.

The limited observations available on blood sugar levels of Mollusca suggest that they are very low. Values of 2–14 mg % glucose have been reported for Aplysia (see Kisch, 1929; Berthoumeyroux, 1935), and even the higher levels recorded for Octopus and Sepia species by Bierry & Giaja (1909), Berthoumeyroux (1935) and Derrien (1938) range only from 20 to 32 mg % glucose. The majority of these blood sugar analyses were based on the Hagedorn & Jensen (1923) technique. Landgrebe & Munday (1954) have shown that this technique may have an inherent blank error of 5 mg % glucose equivalent, and consequently it is not a suitable method for critical analyses of these low molluscan blood sugar levels.